I recently acquired a 2001 Montero (non-sport) Limited. Although it has over 200k miles, It works surprisingly well, however it has trouble with cold starts. If it is warm out, it runs rough for 30 seconds or so then is fine for the rest of the trip. If it is cooler out, it runs rough and has limited power for 2-5 minutes (essentially until it warms up).

I don't get any codes, but I do have one "mystery wire" on the front of the engine on the driver's side. It has a single spade connection and is yellow with a silver trace (see picture). I can't seem to spot any place it would plug into!

I'm wondering if it should plug into a sensor somewhere that I'm not seeing, and since that sensor is unplugged I get terrible cold start performance. I know it is a stretch, but I've got to start somewhere!

So if you recognize my mystery wire, please let me know.

Thanks!

 

That should be AC clutch engagement wire. The connector looks right for that too. It should drop down along the side of the engine and plug to the back of AC compressor.

 

That is what I initially thought as well, and I diagram I found somewhere hinted at the same thing. The strange thing is the AC compressor seems to engage/disengage quite normally (or I would have noticed it during this hot summer!).

Just to verify I put a meter on the mystery wire and it has +12 in the run position no matter if the AC is on or off (and no current if off or in ACC)..

So what would need +12 all the time while the car it running, yet not throw a code for being unplugged?

 

I looked once more under the hood of my 2001 Montero Limited. That wire in your photo is definitely the AC clutch control. It is light yellow and coming from the right spot on the harness. I'd suggest you check what is plugged into AC clutch connector right now. Perhaps you have a constant 12v silly running to it or something else. I'm attaching a photo of the same spot on the engine with the yellow wire.